Such disc dispensing devices may be used in antibiotic susceptibility testing, the agar gel in the culture dish acting as a sterile nutrient medium for a bacteria colony being analysed. The bacteria colony is introduced onto the surface of the gel, usually coming from an original petri dish (preferably after incubation), and the discs are distributed over the surface of the gel by means of the disc dispensing device. Each disc contains a different antibiotic or an antibiotic in a different concentration, so that the effect on the bacteria colony of a plurality of different antibiotics or different concentrations of antibiotics can be simultaneously studied. The use of impregnated discs in this way is well known and will not be described further. In addition, as is usual in this technical field, a bacteria colony normally is put in suspension and brought at the desired concentration before it is transferred to the culture dish. For the sake of simplicity throughout this application the expression bacteria colony is used, but it will be clear to a person skilled in the art that this term refers to any form in which a bacteria colony can be brought which is suitable to transfer to a culture dish. In addition, although the expression “disc” is used throughout this application, this expression in the meaning of this application also refers to discs having a substantial thickness, and thus also encompasses tablets impregnated with antibiotics. In addition the discs need not have a uniform thickness.
A disc dispensing device of the kind as described above is known from GB-A-2 001 432. In this known device the discs are stacked one on top of another in a plurality of elongate cylindrical cartridges provided in a magazine. The discs are biased to an exit end of the cartridge by means of an internal coil spring. Any one cartridge contains only discs impregnated with one particular antibiotic, details of which are displayed on the exterior of the cartridge. A culture dish can be placed on a moveable carriage which is moved in an operating position which is at least almost directly positioned underneath the magazine. After manually positioning the culture dish in the starting position and manually positioning the cartridge in the device the known dispensing device further operates almost completely automatic and consequently provides a preparation for a rapid analysis of clinical samples, thus facilitating its use in situations such as hospitals and laboratories where a considerable number of tests must be made. In the known device a disc is transferred by applying suction to a transfer pipe to thereby hold a disc on the free end of the pipe. The pipe is moved so that the disc is transferred with the pipe from the pick-up position to a releasing position. Upon termination of the suction applied to the pipe the disc is released on the culture dish. Although this known disc dispensing device can operate satisfactorily the internal construction of the magazine and the suction device to transfer discs from a respective cartridge to a specified position on the culture disc is complex and only provides a limited choice in dispensing positions of discs on the culture dish. Furthermore, adaptation of the known disc dispensing device to a different bacteria colony present on the culture dish is relatively time consuming, in particular replacing the magazine and replacing the cartridges within the magazine is time consuming.